Japanese Patent Provisional Publication No. 2002-80629 discloses polyamide porous spherical particles having pores on their surfaces which have a number-average particle diameter of 1 to 30 μm, a BET specific surface area of 100 to 80,000 m2/kg, and a ratio [PDI (particle diameter distribution index)=Dv/Dn] of a volume-average particle diameter (Dv) to the number average particle diameter (Dn) in the range of 1 to 1.5.
The above-mentioned publication describes that the polyamide porous spherical particles can be used for carriers of catalysts, toners of electrophotography, electronics materials of display devices, chromatography, adsorbents in food industries, and medical technology.
WO 2004/043411 describes cosmetic composition utilizing polyamide porous spherical particles which have a number-average particle diameter of 1 to 30 μm, a BET specific surface area of not less than 5 m2/g, a boiled linseed oil-absorbing amount of not less than 200 mL/100 g, a crystallinity (measured by DSC) of not less than 40%, and a particle diameter distribution index of 1.0 to 1.5. This publication describes that the polyamide porous spherical particles are effective for reducing abnormal light-scattering on human skin and shielding defective appearances on human skin such as fine wrinkles and depressions.